The term biotechnology is used to refers to techniques applied to biological systems for the benefit of humans. Biotechnology finds application in many spheres of human activity such as medicines, agriculture, food processing, and other industries. Some specialized branches of biotechnology include genetic engineering, and cell cultures. However biotechnology also included use of biological processes such as fermentation for use of various products.

Genetic engineering deals with modifying genes of living organisms, and cell cultures deal with growing of cells of plants and animals. Fermentation is a process occurring in nature which has been used by human beings for thousands of years for making food products like alcohol, processed cheese and yogurt.

Fermentation is basically any chemical process that takes place as a result of action or growth of bacteria, mould or yeast. For example, sugar is converted in alcohol by the action of yeast, yogurt is made form milk by action of bacteria and penicillin is made by action of fungus or mould.

Bacteria are one cell living organisms that are among the smallest living organisms. Bacteria do not fall clearly in the category of either plant or animals. There are thousands of different types of bacteria. Some of these are harmful to people, but most of them are not harmful, and some of them are actually help internal processes of human body. Some others are used by in external processes such as making yogurt and processed cheese. Some bacteria such as Lactobacillus and Lactococcus have been used for thousands of years across the world to make fermented food preparations such as wine, vinegar, yogurt, and cheese.

Energy yielding oxidation in which the oxidant is an organic compound is called fermentation. In fermentation, organic compounds act both as electron donors and acceptors. Fermentation is of five types:

Fermentation is the process of deriving energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound.This is in contrast to cellular respiration, where electrons are donated to an exogenous electron acceptor, such as oxygen, via an electron transport chain. Fermentation does not necessarily have to be carried out in an anaerobic environment. For example, even in the presence of abundant oxygen, yeast cells greatly prefer fermentation to oxidative phosphorylation, as long as sugars are readily available for consumption